Currently, there are two versions of the iconic weapons of the crafted ones in the game, one that is "dropped" (IE: Items.Preset_"weapon") and one that is crafted (IE: items.[rarity]_"weapon").
Since the crafted items don't have the same IDs as ones that are "dropped," they won't show up on the wall because those are the IDs used to query the inventory for display.
If you're on PC, the easiest way to populate the wall is by spawning a weapon using CET with something like:
Code:
Game.AddToInventory("Items.Preset_Tactician_Headsman", 1)
The wiki has codes for them under technical but it's fairly easy to guess them, like Items.Preset_Burya_Comrade or Items.Preset_Pulsar_Buzzsaw.
As for the fix, either query data for both types (or all the types since there are a bunch of types for rarities) or just have it look for the newer IDs.